A programmable logic controller (PLC) is a piece of automation equipment capable of driving, controlling and/or monitoring one or more processes. For example, the PLC makes it possible to control machines of an assembly line in an industrial plant or to drive automatic handling systems.
A controller generally has a modular-type of architecture and is made up of various modules which may be grouped and connected together in a rack, or more in general referred to as an automation island. The rack itself may include a communication module constituting a transmission bus, commonly referred to as backplane.
The type and number of modules of the controller depends on the needs of the process or processes to be automated. Typically, the controller further includes a power module, a central processing unit and several input-output (I/O) modules, including relays. The I/O modules may further be characterized by the type of signals handled: digital and/or analog signals.
As PLC's may be applied in different environments with varying demands, accordingly various form factors are available to address the requirements related to such different environments. In the typical situation of mounting an electrical installation in an industrial Automation environment, the electrical wiring requires several types of electrical and mechanical interfaces which results in supplying several different types of industrial products pieces and associated references. The number of product variations can quickly rise, even for a simple automation system.
These constraints put a demand on the end user for managing the amount of functional references in order to ensure complete overview of its system, but also to maintain the system by keeping large quantities of spare parts in storage.